As a production method of this type, a method has been proposed in which a trench etching for forming a trench in a thickness direction of a semiconductor layer is performed to form a first pattern portion and a second pattern portion whose mutual side walls face each other across the trench.
JP 2006-220672 A exemplifies an acceleration sensor and a method of manufacturing the acceleration sensor. In the acceleration sensor, one of the first pattern portion and the second pattern portion is a movable electrode, and the other of the first pattern portion and the second pattern portion is a fixed electrode. In this case, the trench etching is performed by etching and removing the semiconductor layer while a protective film is formed on a surface and side walls of the semiconductor layer.